Diagnostic Trouble Code Descriptions
Code CodeNumber Description
12 - No distributor reference pulses to ECM--Code will not be stored in memory and will only be displayed when fault is present. Normal code with ignition "ON" and engine not running.
13 - Oxygen sensor circuit. Engine must operate up to five minutes at part throttle, under road load before code will appear.
14 - Sorted coolant sensor circuit. Engine must operate up to five minutes before code will appear.
15 - Open coolant sensor circuit. Engine must operate up to five minutes before code will appear.
21 - Throttle position sensor circuit. Engine must operate up to 25 seconds at curb idle speed before code will appear.
23 - Open or grounded M/C solenoid circuit.
34 - Vacuum sensor. Engine must operate up to five minutes at curb idle speed before code will appear.
41 - No distributor reference pulses to ECM at specified engine vacuum. Code will store in memory.
42 - EST bypass circuit or EST circuit grounded or open.
44 - Lean exhaust indication. Engine must operate up to five minutes in closed loop and at part throttle before code will appear.
44-45 - At same time--Faulty oxygen sensor circuit.
45 - Rich exhaust indication. Engine must operate up to five minutes in closed loop and at part throttle before code will appear.
51 - Faulty calibration unit (PROM) or improper PROM installation. Engine must operate up to 30 seconds before code will appear.
54 - Shorted M/C solenoid circuit and/or faulty ECM.
55 - Grounded V ref (terminal 21), faulty oxygen sensor or ECM.